Process of rolling sheets



April 1932. R. R. SMITH ET AL 1,852,271

PROCESS OF ROLLING SHEETS Original Filed Oct. 4, 1929 lg'V NTOR. MA /3% M ATTORNEYS Patented Apr. 5, 1932 UNITED STATES rnoonss or ROLLING snnn'rs Continuation of application Serial Our invention relates to methods of rolling metal, particularly iron and steel, in order to produce flat sheets of substantial width and length and of a relatively thin gauge.

This application is a continuation of our Zppigcation Serial No. 397,314, filed October In the production of sheet metal by the.

continuous process great economies are affected, but these economies are dependent for their fullest advantage upon production on a very large scale because of the ex ensiveness of the equipment employed. lso such continuous processes are only carried on to best advantage where large batches, of uniform size pieces are run through the series of mills employed.

Our process is directed to the-production of a varied product, and to the utilization of a rough plate which can be considerably larger and also thinner than the sheet bars used in the customary sheet mill.

One of the objects of our process is to finish rough plate material to desired gauge without reheating. Another object is to do away with the roughing mill operation used in the customary sheet production processes.

lt is readily possible with the use of a con tinuous. two high universal mill or a heavy, two high reversing mill. to produce fairly wide thick pieces of flat metal without restrictions as to length. Such material when made "For the manufacture of and it can be produced today, in widths up to around sixty inches without great difiiculty. Were wider or thinner material to be produced on such mills, a much heavier and more expensive equipment would have to he provided, and furthermore, very careful control of active pass applied to the pieces in the concluding stands of the mill would have to be exercised. This is largely due to the fact that wide pieces of flat material exercise great expansive force tending to separate the rolls of a mill, and thus spring them considerably unless they are extremely heavy,

I and to the further fact that when the metal is thin in gauge. it cannot flow laterally in the mill passes. and further, cannot be confined at the edges by means of mechamcal No. 397,314,111 October 4, 1929. This 1930. Serial No. 429,229].

, down sufficiently to pipe is termed skelp application filed February 18,

guides. Without very careful control of the active passes in the rolls, wide, thin material will therefore tend to elongate diflerently along one zone than along another, and will buckle or travel in a curve and run intothe necks of the mill rolls.

Our process utilizes with great economy, a rough product which is produced on mills, such asskelp mills or plate mills, where the difficulties last noted are not encountered, where the equipment is not relatively expensive, and the care in rolling is not nearly so paramount in importance. Heretofore the material used for rolling sheets has been called sheet bar. Sheet bars are too narrowto serve in our process,

form proper pack formingmaterial, we can finish such a pack in our process without a reheating.

Ordinarily, the product which we employ in our process is the cheaply rolled platematerial, which material is cut into lengths which will correspond with the width of the final product, the pieces being rolled to a thickness which will give the desired length in the final product when reduced, to the required gauge. We may also roll the plate sections lengthwise of the precedin rolling step. We can also employ rough p ate. produced in fairly thick gauges on the modern continuous process mills, which can furnish this material with great economy.

It should be noted that in order to provide ail-economical process of producing sheets, rolling equipment is called for which will finish therough product rapidly enough to warrant the use of a continuous furnace to supply the material in proper heated condl- 'tion for rolling, and which will dispense wlth the intermediate reheating of the product during the finishing.

This is provided for in our process by the use of a three-high mill, through which the pieces are passed to and fro, being rolled first in one direction and then in the other. WVe preferably employ a tilting table at one side of the mill to catch the pieces as they are rolled. and lift them intothe return pass, and heat the starting material in a contlnuous furnace at the entering side of the mill.

but if they are roughed It would be impractical in any three-high mill, such as has been employed in the past in rolling plate, to finish the lighter gauges by our process, usual proportions may be used for the heavier gauges. This is because when the pieces come to the three-high mill inour process they are wide and very rapidly reduced to become quite thin, with corresponding rapid cooling, and maximum reductions per pass call for more rigid proportions COIHbIDQd with much smaller middle rolls than are ordinarily used in three-high mills. The proportions of the mills used in our process more closely resemble the modern continuous mills,

' which, however, are four-high mills.

' the use. of

In our process we provide for a three-high mill with a central roll of small diameter, and backing up rolls of considerably larger diameter which will result not only in a mill which is quite rigid as to its resistance to springing, but which permits the greater reduction of the pieces per pass than is possible with large diameterrolls engaging the piece.

It is further advisable in our process to use very heavy housings in which the rolls are mounted, and to provide against elasticity in the roll supports, "so that heavy drafts can be imparted. Furthermore, we preferably keep the rolls of the mill cold with water sprays. p

So far as we are advised, it has never been proposed to roll acks or multiples of flatpieces in a three-hlgh mill for one reason, because no mills have been designed for such a purpose, and because the process requires wide plate material as distinguished from narrow bars for reduction to sheets without reheating, which has not. occurred to those skilled in the art. In our process we reduce flatmetal in multiples in the three-high mill, and effect great economies thereby.

As a guide in connection with the structure of the three-high mill, we have carried on' our process in a mill with closed type housings, having a middle roll of a'len'gth of fortyeight to ninety-six inches, and a thickness of working barrel of fifteen inches, together with backing u rolls of like length of barrel, but with a t ickness of thirty inches. In this mill the lower roll is driven, and the middle or smallroll is idle. We do not con fine our invention to the use of a mill of this one size, but believe that the thickness of the rolls'proportionate to length is most desirable in a mill of the width used by us.

, We have indicated in the appended drawings a diagram of a suitable mill arrangement to be used in our process.

In the drawings Figure 1 is a diagram or plan of the mill. Figure 2 is a vertical cross-section taken through the three-high mill.

The furnace 1, which is preferably a conalthough three-high mills of the tinuous furnace, delivers single thickness I pieces to the table 2. The mill has the small central roll 3, and the outer rolls 4, 4, which I \mill between the middle and lower roll, and

then back betweenthe middle and upper roll until reduced to a length suitable for matching, whereupon the two pieces are matched, and the rolling continued in the same manner. 1

Instead of starting with rough plate or thin barproduced in a continuous mill or b continuous process, we may start with roug 1 plate produced in any desired way.

Furthermore, referring now to the prodnot of the modern continuous process mills,

wherein the active pass is accurately controlled and'large, heavy equipment provided,

we can start our process with pairs which have not been given any treatment but a heating treatment, after leaving the continuous mill, if they are of thin enough gau e to permit this. The reason why we can do this is because the pieces rolled in such a process have a very definite shape given to them and the shape of the pairs furnished to the three-high mill, as in our process, can readily be determined.

Furthermore, we can start our process with a pair of pieces passed through a two-high roughing mill of usual type, provided care is taken in the roughing mill to produce pieces to be matched which have a definite contour.

In our process, once the individual pieces or packs have been started into the threehigh mill, no reheating is given to the pieces,

and they are rolled back and forth until they have been sufficiently ,ducing finergauges three rough plates may be started through the mill, the catcher holding one and passing one for the first few passes, and then matching all three, and finishing the pieces as a pack of three.

In one typical process the individual pieces from a skelpmill of.2 inches thickness are fed through once by the roller, and back once by the catcher, whereupon the roller matches them, and three more passes 'are or pack which has been formed i reduced. In pro-- given to the pair, giving a product of .062

inches or 16 gauge. We find that mechanically operated tilting and catching tables are of advantage in'gaining fullest benefit from our process.

In another typical process, pieces from the modern continuous mills, having a thickness ofy.085 inches, can be rolled down in three to five passes, depending upon the a pair, and this pair then passed to and froin the three-high mill without any reheating to a finished thickness of .05 inches or 18 gaugea These, of course, are merely given as ex-\ amples of what may be dpne with ourproc- .ess, as thicker or thinner packs or pieces may be used to start with than in any of the examples, and thinner or thicker gauges of final product formed. The limitations in final gauge depend upon the necessity for reheating it the pieces get too cold, the thickness of the starting material and number of pieces in the pack, two being the best numher in our experience.

We believe that it is a necessary feature of our process to finish to final gauge as a pair, or in multiple without doubling, which of itself is novel in sheet mill'practice'except for certain continuous processes of sheet rolling to which we have referred. If do11- bling were attempted, the time lost would require' a reheating, which would cause loss of time and great expense.

By using a three-high mill of great rigidity and heavy draft, using it to reduce the starting material by passes in single thickas. b

, pair which itself ness, or using a roughing mill to form a is rapid and economical, and then finishing in two thicknesses in the three-high mill, we have been able to take the product from a continuous furnace, op-

erating on an economical basis and very greatly reduce the cost of producing sheet metal over the hand mill rolling art. Indeed, for anything but a very large production, the results of using our process have een more economical than any process of sheet rolling known at the present time, including the continuous mill production, and continuous process, tandem rolling.

The use of the water cooling of the threehigh mill of our invention is'ef importance in a number of respects. The mill, of course. must have the small diameter middle roll and thus we are permitted to gain great reductions in each pass Without excessive and the rigidity of the springing of the rolls. In spite of this, however, the presence ofa film of water on the rolls, thus keeping, them cold, makes our process much more practical.

The shape of the rolls is easier to control because-there is little or no variation due to pressure, mill inhibits great differential heating of the rolls. Due to the tact that the pores of the metal in the rolls are kept closed because of the low temperature thereof during rolling, the surtive size of inner face of the rolls are not subjected to marking, and the flow of water over the rolls tends to remove tiny particles of grit, in the short idle time between passes. It is practical to use higher initial temperature of the pieces with the water cooled three-high mill, because with water cooled rolls, effecting desired reductions per pass with a minimum of applied pressure, the tendency of the parts of a pack to become stuck together or to patch and stick due to partial welding of -the surfaces is largely done away with. This last seems to be due to the fact that setting and patching are the results of combined pressure and temperature, setting taking place when both are high, and patchingwhen both are low, and that with the water cooled three-high mill with small diameter working roll, the combination of pressure and temperature will not result in patching or sticking.

The advantage in, accuracy of production of the from the fact that we can our three-high mill, and then reheat it and process of our invention will be evident finish a pack on i roll it in doubled or re-matched shape on an ordinary two-high hot hand mill, without We do not know of whereby packs of substantial width can be rolled by repeated passes on one mill, and then reheated, doubled or matched to greater thickness, and successfully finished on another mill on a commercial basis to light gauges. This is possible in our process, because the water cooled three-high mill operating as it does, produces packs of a very accurate contour, and the finishing roller can arrange a proper setting for his finishing m ll to take care of the packs furnished to him, and set the pack so that it can be rolled tight.

As compared to the customary process of finishing sheets in pairs and packs, the dif' ference of our process is apparent.

As compared to process in which the threehigh mill has been employed in rolling plates, using a tilting catching table, and reducing in the reverse as well as the forward pass,

the structure of mill as to rigidity, comparacommercially onthethree-high plate mill.

any process in the past initial passes of the and outer rolls. and lack of 7 Having thus described our invention, what we claim as new and desire to secure by Letters Patent, is

1. In a process of rolling sheets, the steps of passing heated pieces longer in direction of rolling than ordinary sheet bars singly, first between a small central roll and large bottom roll, and then back between the small central roll and a large top roll,'sufiiciently to reduce the pieces to pack forming material, then matching the single pieces into a pack and without reheating, continuing to pass the pack forth and back in the same manner between the same rolls, the rolls so employed being kept cold enough tosubstantially eliminate change of shape due to heatmg.

2. In a process of rolling sheets, the steps of passing heated sections of continuously rolled plates longer in direction of rolling than ordinary sheet bars singly, first between a small central roll and large bottom roll, and then back between thesmall central roll and a large top roll, sulficiently to reduce the pieces to pack forming material, then matching the single pieces into a pack and without reheating, continuing to pass the pack forth and back in the same manner betweenthe same rolls. I

3. In a process of rolling sheets,-the steps of passing heated pieces longer in direction of rolling than ordinary sheet bars singly, first between a small central roll and large bottom roll, and then back between the small central roll and a large top roll, sufiiciently to reduce the pieces to pack forming material, then matching the single pieces into a pack and without reheating, continuing to pass the pack forth and back in thesame manner between the same rolls, said pieces being furnished to the first pass from acontinuous furnace.

' 4. In a process of rolling sheets that step which consists in rolling a pack of heated flat material longer in direction of rolling than ordinary sheet bars, first between a small central roll and large bottom roll, and then back between the smallcentral roll and a large top roll, and continuing in this sequence without doubling-to desired gauge, the rolls so employed being kept cold enough to substantially eliminate change of shape due to heating. I r

5. In aprocess of. rolling sheets that step which consists in rolling a pack of heated flat'material, first between a small central roll and large bottom roll, and then back between the small central roll and large top roll, and continuing in this sequence without doubling to finished gauge, the pack being formed of material given at least one pass between said rolls, previous to being matched.

6- In a process of rolling sheets, the steps of passing heated pieces longer in direction '65 of rolling than an ordinary sheet bar singly,

first between a small central roll and largev bottom roll, and then back between the small central roll and a large top roll, sufliciently to reduce the pieces to pack forming material, thenmatching the single pieces into a pack and without reheating, continuing topass the pack forth and back in the same man ner between the same rolls, the said rolls being kept cold by water during the process, sufficiently to eliminate substantial change of shape due to heating and to maintain the roll surface and avoid setting and patching.

7. In a process of rolling sheets, the stepsof passing heated pieces singly, first between a small central roll and large bottom roll, and then back between the small central roll and alarge top roll, sufficiently to reduce the pieces to pack forming material, then matching the single pieces into a pack and without reheating, continuing to pass the pack forth and back in the same manner between the same rolls, the said rolls being kept covered with a film of water during the process, the said pieces furnished at the start of the process being longer in the direction of rolling than a sheet bar.

8. In a process of rolling sheets that step which consists in rolling a pack of flat material, first between a small central roll and large bottom roll, and-then back between the small central roll and a large top .roll, and continuing in thissequence without doublin to desired gauge, the rolls being kept covere with a film of water during the process.

9. In a process of rolling sheets that step which consists in rolling a pack of flat material, first between a small central roll and large bottom roll, and then back between the small central roll and a largetop roll, and

continuing in this sequence without doubling to desired gauge, the rolls being kept covered by afilm of water during the process so as to eliminate substantial change of shape thereof due to heating, and then doubling or matching and reheating the packsand rolling same ,on a finishing mill.

RUSSELL B. SMITH. WILLIAM F; SONGER. 4 LAMBERT A. SALENDER. 

